How Does it Work?

A Sensofoil® membrane potentiometer PET-Magnet consists of a resistive track printed onto the bottom PET foil layer and a collector track printed onto the top PET foil layer. These layers are seperated by a so-called spacer. Only when the layers connect through mechanical pressure using a wiper a signal is produced.

For contactless operation, an additional layer is added using a ferromagnetic material. This ferromagnetic strip is pulled by a magnet, pressing the collector foil against the resistive track, therefore creating a contact. With the correct dimensions, linear paths and angles can be measured contactless, even through enclosures.

Ideally, a low DC voltage is connected to the resistive track and tapped at the collector track in the form of a voltage divider. A linear relation exists between the length of the resistive track, or the angle of the resistive track for rotary sensors, and the applied voltage. At 50% of distance traveled, 50% of the applied voltage is measured.

Quality characteristics of the Sensofoil® membrane potentiometers are resistance values, their corresponding tolerances and the non-linearity. The non-linearity represents the actual deviation of the output signal to an ideal reference line and is expressed as a percentage of the applied supply voltage.